The alcohols of long chain olefins having about 12 to 20 carbon atoms have considerable commercial importance in a variety of applications, including detergents, soaps, surfactants, and freeze point depressants in lubricating oils. These alcohols are produced by any one of commercial processes, such as the oxo or hydroformylation of long chain olefins. Typical long chain alcohols are the commercially available NEODOL.RTM. alcohols made by Shell Chemical Company, the EXXAL.RTM. alcohols available from Exxon Chemical, and the LIAL.RTM. alcohols available from Enichem.
In the manufacture of the NEODOL.RTM. alcohols, a predominantly linear olefin feed is subjected to hydroformylation by reacting carbon monoxide and hydrogen onto the olefin in the presence of an Oxo catalyst to form an alcohol. In excess of 80% of the number of alcohol molecules in the resultant alcohol composition are linear primary alcohols. Of the branched primary alcohols in the composition, substantially all, if not all, of the branching is on the C.sub.2 carbon atom relative to the hydroxyl bearing carbon atom. These alcohols can subsequently be converted to anionic or nonionic detergents or general surfactants by sulfonation or ethoxylation, respectively, of the alcohol. Also known as anionic surfactants for detergents are the alcohol-ethoxysulfates.
The NEODOL.RTM. line of alcohols have met with considerable commercial success as detergent precursors because the NEODOL.RTM. alcohol compositions can be economically produced with high yields of linear alcohols. The desire to use linear alcohols as intermediates for detergent grade surfactants exists because it is generally recognized that linear alcohols biodegrade, while the branched long chain alcohol sulfonates exhibit poor biodegradability. Since detergents and soaps used by consumers for washing are ultimately released into the environment, the need to provide a surfactant or detergent which biodegrades is well recognized.
For example, U.S. Pat. No. 5,112,519 describes the manufacture of a surfactant by oligomerizing C.sub.3 and C.sub.4 olefins through a surface deactivated ZSM-23 catalyst to form oligomers, hydroformylating the oligomer, and recovering a semi-linear alcohol composition having less than 1.4 methyl branches, and whose branching is limited to methyl branches. The alcohol can be ethoxylated and/or sulfated and is reported to be biodegradable, and further have improved low temperature properties compared to isotridecyl alcohol. Retaining the linearity of the alcohol composition to less than 1.4, along with obtaining methyl branching were important considerations to achieving a biodegradable surfactant. It would be desirable, however, to obtain a biodegradable surfactant without limiting the branching to methyl branches, without limiting the branching to under 1.4, and without limiting oneself to a ZSM 23 surface deactivated catalyst. It would also be desirable to make a biodegradable surfactant without conducting oligomerization reactions through zeolite catalysts, which are expensive and may coke up or be used up quickly if one needs to build chain length through the catalyst.
Another product, EXXAL.RTM. 13, is derived from propylene oligomerization through acid catalysis to a wide range of mono-olefins, the range having an average of C13s being distilled out, but containing some olefins in the C.sub.10-15 range. The olefin is then subjected to hydroformylation using an oxo process. EXXAL.RTM. 13 is reported to be a 3-4 methyl branched tridecyl-alcohol known for its use in lubricants and in those detergent formulations which do not require rapid biodegradation. This is because EXXAL.RTM. 13 only slowly biodegrades. While such a high amount of branching is not necessary, it would be desirable to make a surfactant having a high amount of branching for detergency which is nevertheless readily biodegradable.
The dimerization of low carbon numbered olefins is generally known in the Dimersol.RTM. process. This process is a catalyzed liquid phase oligomerization, primarily dimerization, of propylene or butylene. The process was developed by the Institute Francais du Petrole. The process uses generally a catalyst prepared by reacting a nickel compound with a hydrocarbyl aluminum halide. The primary product is the dimer of the propylene or butylene with smaller amounts of the trimer and tetramer being present. General discussion of the Dimersol Process can be found in Hydrocarbon Processing, Vol.89, pp 143-149, May, 1980 and Vol. 91, pp 110-112, May, 1982.
U.S. Pat. No. 4,584,411 reports that higher oligomers made from proplyene and butylene, i.e., the small quantities of trimers and tetramers forming up to C.sub.12 oligomerized olefins, are fractionated out of the dimerized stream composed mainly of C.sub.6-8 dimerized olefins, and then subjected to conversion to alcohols as intermediates in detergents and lubricant products. However, the dimerized stream was first treated with a tantalum (V) halide/oxide-inorganic oxide catalyst for the purpose of oligomerizing out the more highly branched materials, thereby producing a linear product which was hydroformylated. It was recognized that the oligomerization process produced branched materials, which were reported to be undesirable, and hence, treated. It would be desirable, however, to utilize a process in which one is not reliant on using a proplyene or butylene feed prior to dimerization, which produces primarily only C.sub.6 or 8 dimerized olefins, and which does not rely upon utilizing minor quantities of trimers and tetramers which may contain quaternary carbon atoms, and which can form both odd and even numbered olefins, and which, contrary to the direction of the teachings in U.S. Pat. No. 4,584,411, form highly branched primary alcohol compositions which are biodegradible.
Similarly, U.S. Pat. No. 4,959,491 reports that C.sub.12 olefins can be manufactured in a two-step dimerization process by dimerizing propylene, fractionally distilling out about 70 to 82% of linear C.sub.6 dimer product (special extraction steps must be used to obtain a higher purity of linearity), and subjecting the product again to dimerization to produce a semi-linear C.sub.12 olefin comprised of a mixture of linear and mono-branched olefin. These products are then reacted with benzene and sulfated to produce biodegradable alkylbenzene sulfonates. No mention is made of the suitability of these types of olefins for the manufacture of primary alcohol compositions. Further, as noted above, it would be desirable to manufacture an high carbon chain olefin without limitation to dimerizing propylene, and without the necessity for utilizing multiple dimerization steps. It would also be desirable to make primary alcohol compositions having a higher number of branches than what one would expect with a mixture of linear and mono-branched olefins.
U.S. Pat. No. 5,196,625 describes a dimerization process for producing linear and/or mono -branched C10 to C28 olefins using dimerization catalysts, for the production of biodegradable alkylbenzene sulfonates detergents by alkylating the olefins onto benzene. While this patent reports the use of a C.sub.5 to C.sub.10 feed of olefins, no mention is made of using the dimerized olefins to make alcohols. Further, the patentee reported that it is generally recognized that "linear and mono-branched alkyl aromatic sulfonates are generally much more readily biodegraded than multibranched alkyl aromatic sulfonates and, hence, much more desirable as detergents." The patentee sought to ensure that the olefins made were substantially linear and monobranched to avoid sacrificing biodegradibility. However, we have found it desirable to make highly branched alcohols to improve cold water detergency of detergent alcohol sulfates.
There exists a growing need to find alcohol intermediates for the manufacture of sulfate detergents which are both biodegradable and exhibit good detergency at cold wash temperatures, that is, increasing branching which we have found to increase cold water detergency, but without sacrificing ready biodegradibility. The process employed should be simple and flexible enough to produce a wide variety of products.